Double-stranded cDNA fragments were synthesized from hepatitis A virus (HAV) RNA and inserted into the Pst I site of pBR322. The identity of cloned cDNA was established by demonstrating its hydridization to RNA from HAV-infected tissue culture cells but not to RNA from uninfected cells. Genomic length RNA of approximately 7500 nucleotides was the predominant species that hybridized with the HAV cloned DNA. Restriction endonuclease digestion and hybridization between subgenomic fragments yielded a map of overlapping cloned cDNAs which includes 99% of the viral genome. A partial sequence from the 3 foot end of the genome contained 890 bases in an open reading frame preceding stop codons, 60 bases of a noncoding region, and a tract of poly(A).